Control of Gene Expression Flashcards
What is gene regulation?
The mechanisms that act to induce or repress the expression of a gene.
What are the different levels at which gene expression can be regulated?
- DNA level
- RNA level
- Protein level
What types of gene expression regulation exist in prokaryotes?
- Inducible
- Repressible
What is the definition of gene expression?
The process by which information from a gene is used to synthesize functional gene products, usually proteins.
List some mechanisms involved in gene regulation.
- Structural and chemical changes to the genetic material
- Binding of proteins to specific DNA elements
- Modulation of translation of mRNA
What is the most important point for regulation of gene expression?
Initiation of transcription.
What are cis-acting elements?
DNA sequences in the vicinity of the structural portion of a gene that are required for gene expression.
What are trans-acting factors?
Usually proteins that bind to cis-acting sequences to control gene expression.
What are constitutively expressed genes?
Genes that are always expressed, such as RNA polymerase and glycolysis enzymes.
What are regulatable genes?
Genes expressed only under certain circumstances.
What are the two types of regulatable genes?
- Inducible – usually ‘off’ but can be switched ‘on’
- Repressible – usually ‘on’ but can be switched ‘off’
What is the trp operon?
A repressible operon involved in tryptophan synthesis in E. coli.
What is the lac operon?
An inducible operon involved in lactose metabolism in E. coli.
What role does allolactose play in the lac operon?
It acts as an inducer that binds to the repressor, allowing transcription to occur.
What happens when glucose is present in relation to the lac operon?
E. coli uses glucose first, inhibiting the lac operon until all glucose is consumed.
True or False: RNA interference (RNAi) is a natural mechanism used to inhibit mRNA translation.
True
What is the function of RNAi?
To inhibit viral expression and control gene expression.
Fill in the blank: The _______ operon is usually ‘off’ but can be switched ‘on’ by the presence of lactose.
lac
Fill in the blank: The _______ operon is usually ‘on’ but can be turned ‘off’ when tryptophan is present.
trp
What are some factors that influence transcription initiation?
- RNA Polymerase binding to the promoter
- Transcription factors binding
What is alternative splicing?
A mechanism in eukaryotes that allows for the production of different mRNA variants from a single gene.
What is mRNA silencing?
A mechanism that regulates gene expression by preventing translation of mRNA.
What is post-translational control?
Modification of proteins after they have been synthesized.
What are DNA binding proteins?
Proteins that recognize and bind to specific DNA sequences to regulate gene expression.
What is the role of the promoter in gene expression?
It is the region where RNA polymerase binds to initiate transcription.
What does the term ‘epigenetics’ refer to?
The study of changes in gene expression that do not involve alterations to the underlying DNA sequence.
What is a key observation about cells in a eukaryotic organism?
The vast majority contain the same DNA but have different types of cells with different functions.
